One process for manufacturing a semiconductor device such as a flash memory may include a substrate processing process such as a process for loading a substrate, which includes a gate electrode whose sidewall is exposed by etching, into a process chamber; and a process for performing oxidation by supplying a hydrogen-containing gas and an oxygen-containing gas, which are excited with plasma for the substrate, into a process chamber. In such a substrate processing process, the etching damage, which is caused as the etching is performed on the sidewall of the gate electrode formed of a polysilicon film, is recovered by performing the oxidation. However, for example, when the sidewall of the polysilicon film is recovered, the polysilicon film may be oxidized to an excessive extent exceeding a desired level.
Therefore, to inhibit excessive oxidation of the polysilicon film, for example, a substrate processing process for forming a nitride layer on a polysilicon film in advance may be performed by supplying a process gas including nitrogen atoms excited with plasma into a process chamber and supplying a process gas into a substrate before oxidation.
For example, although a nitride layer is formed to achieve the above-described objects, an oxygen-containing layer such as a native oxide layer may be formed on a substrate by exposing the substrate to the atmosphere through transfer of the substrate before formation of the nitride layer. When the nitride layer is formed on the substrate on which such an oxygen-containing layer such as a native oxide layer is formed by supplying a process gas containing nitrogen atoms, it is impossible to increase a concentration of the nitrogen atoms in the nitride layer. Therefore, when etching damage of sidewalls of a polysilicon film caused by oxidation is recovered, there have been cases in which excessive oxidation of the polysilicon film may not be inhibited.